Giant predators in a tropical Cretaceous sea

PUBLICATION — Cortés D. and Larsson HCE (2026) The Paja Formation of Colombia records uniquely high biodiversity during a Biotic Inflection in an Early Cretaceous Gondwanan marine ecosystem. Front. Ecol. Evol. 14:1848892. doi: 10.3389/fevo.2026.1848892

Figure reproduced from Cortés and Larsson 2026 (fig. 7), Frontiers in Ecology and Evolution, under the Creative Commons Attribution License CC BY. Paleoart by Juan Giraldo.

The Paja Formation (Colombia) preserves an exceptional fossil record of a tropical sea 120 million years old. Findings include pliosaurs over 10 metres long, large elasmosaurs, specialized ichthyosaurs, marine turtles, fishes, ammonites, early crabs, dinosaurs, and more. Its food web reached seven trophic levels, more than the six seen in the most complex modern ecosystems. This Early Cretaceous ecosystem was shown as reflecting a Biotic Inflection, that is, an overlap of declining relict lineages and emerging radiations, a period when marine life was reshaped after the Jurassic–Cretaceous crisis.